A volcano near Rome is showing signs that a massive eruption is brewing

On the outskirts of Rome, an ancient volcano — long thought to be
extinct — is showing signs that another massive eruption is
brewing.

But don’t panic just yet. Scientists say it’s not likely to
blow its top for another 1,000 years or so.

Colli Albani is a volcanic complex spanning a 9-mile
semicircle of hills, located approximately 19 miles away from the
city center of Rome. It last erupted 36,000 years ago, prompting
geologists to classify it as extinct.

However, according to a new study published in Geophysical Research
Letters, scientists have observed new steam vents,
earthquakes, and a rise in ground level in the surrounding area,
suggesting that a bubble of magma is forming beneath the surface.
These observations, along with evidence from satellite data,
suggest that the volcano is starting a “new eruptive cycle”
— in other words, it is rumbling back to life.

Researchers found that the ground is inflating at a rate of
about 0.08 inches (2 millimeters) every year in areas where steam
vents are appearing. Over the last 200,000 years, they said, the
ground has risen a total of 164 feet. For thousands of years, the
magma bubble under the volcano was trapped by pieces of land that
have recently begun sliding against each other. If they slide
enough, an eruption becomes possible.

Records of its previous eruption suggests that under the
right conditions, Colli Albani could produce an eruption as
destructive as Mt. Vesuvius, which destroyed Pompeii
in 79 AD. A potential future eruption of Colli Albani could
generate massive, far-reaching clouds of smoke and ash, unleash
lava that would roll down the slopes at fast speeds, and send
rocks raining on nearby cities. Rome itself would only be
severely affected if the wind blew in the right direction, but
the city’s suburbs (which reach all the way to the base of the
volcano) would be devastated.

Thankfully, researchers say the volcano won’t blow
unexpectedly. Sufficient pressure still needs to build for about
1,000 years before an eruption is even possible. Then, even when
the conditions are just right, the explosive eruption would
likely be preceded by initial states of moderate activity.